Method of making printed circuit board structure including a closed cavity with vias

ABSTRACT

A method of making a printed circuit board structure including a closed cavity is provided. The method can include the steps of forming a cavity in a core structure of a core layer, laminating each of a top surface and a bottom surface of the core structure with an adhesive layer and a metal layer to prepare a laminate structure and cover the cavity to define a closed cavity. The method also includes forming vias through the laminate structure, and patterning the metal layers in the laminate structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57, andshould be considered a part of this specification.

BACKGROUND Field

Embodiments of the invention relate to electronic systems, and inparticular, to methods of making printed circuit boards forradio-frequency (RF) electronics.

Description of the Related Art

Printed circuit board (PCB) structures are commonly used in electronics.Some printed circuit board structures include exposed cavities.

SUMMARY

Accordingly, there is a need for an improved printed circuit boardstructure that includes an enclosed cavity, such as an air cavity, and amethod for manufacturing it. In one aspect, the cavity can function asan antenna.

In accordance with one aspect, a closed cavity printed circuit board isprovided. The closed cavity printed circuit board comprises a substratelayer, a first metal layer disposed over the substrate layer, a corelayer disposed over the first metal layer, and a second metal layerdisposed over the core layer. The core layer defines a closed cavitybetween the first and second metal layers.

In accordance with another aspect, a radiofrequency module is provided.The radiofrequency module comprises a printed circuit board including asubstrate layer, a first metal layer disposed over the substrate layer,a core layer disposed over the first metal layer and defining a closedcavity, a second metal layer disposed over the core layer, a second corelayer disposed over the second metal layer and a third metal layerdisposed over the second core layer, the third metal layer forming aplanar antenna.

In accordance with another aspect, a wireless mobile device is provided.The wireless mobile device comprises an antenna defined by a printedcircuit board including a substrate layer, a first metal layer disposedover the substrate layer, a core layer disposed over the first metallayer and defining a closed cavity, a second metal layer disposed overthe core layer, a second core layer disposed over the second metallayer, and a third metal layer disposed over the second core layer, thecavity defining the antenna and configured to radiate in a firstdirection. The wireless mobile device also comprises a planar antennadefined by the third metal layer and spaced apart from the cavity andconfigured to radiate in a second direction different than the firstdirection, and a transceiver configured to process signals received bythe antenna.

In accordance with another aspect, a method of making a closed cavityprinted circuit board is provided. The method comprises forming a cavityin a core structure of a core layer, laminating each of a top surfaceand a bottom surface of the core structure with an adhesive layer and ametal layer to prepare a laminate structure and cover the cavity todefine a closed cavity. The method also comprises forming vias throughthe laminate structure, and patterning the metal layers in the laminatestructure.

In accordance with another aspect, a method of making a closed cavityprinted circuit board is provided. The method comprises providing a corelayer having a core structure between a pair of metal layers, removingthe pair of metal layers from the core layer, forming a cavity in thecore structure, and laminating the core structure with an adhesive layerand metal layers over a top and bottom surface of the core structure toprepare a laminate structure and cover the cavity and define a closedcavity. The method also comprises forming vias through the laminatestructure, patterning the metal layers in the laminate structure, andattaching the patterned laminate structure to a substrate.

In accordance with another aspect, a method of making a printed circuitboard is provided. The method comprises providing a printed circuitboard structure having an open cavity defined in a core layer, laying acover layer over the printed circuit board structure so that the coverlayer extends over the cavity to cover the cavity and define a closedcavity, laminating a board over the cover layer, the board having atleast two layers, and forming one or more through bores through thecover layer. The method also comprises plating the one or more throughbores to form one or more vias between a top metal layer of the boardand a bottom metal layer of the board.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of one example of a wireless devicethat can include one or more closed-cavity antennas.

FIG. 2 is a block diagram of another example of a wireless device withan integrated antenna module.

FIG. 3 is a schematic view of one embodiment of a printed circuit boardstructure with a closed cavity.

FIG. 4A is a flow diagram of a method for making the printed circuitboard structure of FIG. 3.

FIG. 4B is a block diagram of a method of manufacturing a printedcircuit board with a closed cavity.

FIG. 5 is a schematic view of an embodiment of a printed circuit boardstructure with a closed cavity.

FIG. 6A is a flow diagram of a method of making the printed circuitboard structure of FIG. 5.

FIG. 6B is a block diagram of a method of manufacturing a printedcircuit board with a closed cavity.

FIGS. 7A and 7B illustrate example antennas according to certainembodiments.

DETAILED DESCRIPTION

The headings provided herein, if any, are for convenience only and donot necessarily affect the scope or meaning of the claimed invention.

The following detailed description of certain embodiments presentsvarious descriptions of specific embodiments. However, the innovationsdescribed herein can be embodied in a multitude of different ways, forexample, as defined and covered by the claims. In this description,reference is made to the drawings where like reference numerals canindicate identical or functionally similar elements. It will beunderstood that elements illustrated in the figures are not necessarilydrawn to scale. Moreover, it will be understood that certain embodimentscan include more elements than illustrated in a figure and/or a subsetof the elements illustrated in a figure. Further, some embodiments canincorporate any suitable combination of features from two or morefigures.

There is a desire for an improved packaging technology. The package caninclude a laminated substrate with an antenna. An electronic componentor die, such as a radio frequency (RF) component, can be disposed alonga bottom layer of the laminate substrate. Solder bumps can be disposedaround the electronic component and electrically connected to the groundplane. The solder bumps can attach the module to a carrier or directlyto a system board. The electronic component can be surrounded by solderbumps. For example, outside edges of the electronic component can haveground solder bumps that are connected to the ground plane by way ofvias. The ground solder bumps around the electronic component can beconnected to ground of a carrier or system board.

One aspect of this disclosure is a module that includes a multi-layersubstrate, an antenna, a radio frequency (RF) component, and conductivefeatures disposed around the RF component. The multi-layer substrate hasa first side and a second side opposite to the first side. Themulti-layer substrate includes a ground plane. The antenna is on thefirst side of the multi-layer substrate. The RF component is on thesecond side of the multi-layer substrate such that the ground plane ispositioned between the antenna and the RF component. The conductivefeatures are disposed around the RF component and electrically connectedto the ground plane. The conductive features and the ground planeconfigured to provide shielding for the RF component.

Another aspect of this disclosure is an RF circuit assembly thatincludes a laminate substrate having a first side and a second sideopposite the first side, an antenna on the first side of the laminatesubstrate, an RF component attached on the second side of the laminatesubstrate, and a plurality of solder bumps disposed around the RFcomponent. The laminate substrate includes a ground plane that ispositioned between the antenna and the RF component. The solder bumpsform at least a portion of an electrical connection to the ground planeto thereby form at least a portion of a shielding structure around theRF component.

Another aspect of this disclosure is system board assembly that includesa laminate substrate having a first side and a second side opposite tothe first side, an antenna on the first side of the laminate substrate,an RF component attached on the second side of the laminate substrate, aplurality of solder bumps disposed around the RF component, and a systemboard. The laminate substrate includes at least one layer forming aground plane. The ground plane is positioned between the antenna and theRF component. The plurality of solder bumps are electrically connectedto the ground plane. The system board can include ground padselectrically connected to ground plane by way of the plurality of solderbumps such that a shielding structure is formed around the RF component.

Overview of Wireless Devices

FIG. 1 is a schematic block diagram of one example of a wireless ormobile device 11. The wireless device 11 can include one or moreantennas implementing one or more features of the present disclosure,such as one or more closed cavity antennas.

Closed-cavity antennas can be used within the wireless or a mobiledevice 11 implementing a 5G telecommunication standard that may utilize30 GHz and 60-70 GHz frequency bands. Additionally, the 3G, 4G, LTE, orAdvanced LTE telecommunication standards can be used in the wireless ormobile device 11, as described herein.

The example wireless device 11 depicted in FIG. 1 can represent amulti-band and/or multi-mode device such as a multi-band/multi-modemobile phone. By way of examples, Global System for Mobile (GSM)communication standard is a mode of digital cellular communication thatis utilized in many parts of the world. GSM mode mobile phones canoperate at one or more of four frequency bands: 850 MHz (approximately824-849 MHz for Tx, 869-894 MHz for Rx), 900 MHz (approximately 880-915MHz for Tx, 925-960 MHz for Rx), 1800 MHz (approximately 1710-1785 MHzfor Tx, 1805-1880 MHz for Rx), and 1900 MHz (approximately 1850-1910 MHzfor Tx, 1930-1990 MHz for Rx). Variations and/or regional/nationalimplementations of the GSM bands are also utilized in different parts ofthe world.

Code division multiple access (CDMA) is another standard that can beimplemented in mobile phone devices. In certain implementations, CDMAdevices can operate in one or more of 800 MHz, 900 MHz, 1800 MHz and1900 MHz bands, while certain W-CDMA and Long Term Evolution (LTE)devices can operate over, for example, about 22 radio frequency spectrumbands.

In certain embodiments, the wireless device 11 can include an antennaswitch module 12, a transceiver 13, at least one antenna package 22,power amplifiers 17, a control component 18, a computer readable medium19, a processor 20, and a battery 21.

The transceiver 13 can generate RF signals for transmission via theantenna 22. Furthermore, the transceiver 13 can receive incoming RFsignals from the antenna 22. The at least one antenna package 22 caninclude one or more antennas defined by a closed cavity printed circuitboard (PCB), such as any of those described herein. The antenna packagecan also include other types of antennas, such as a dipole antenna, forexample.

It will be understood that various functionalities associated withtransmitting and receiving of RF signals can be achieved by one or morecomponents that are collectively represented in FIG. 1 as thetransceiver 13. For example, a single component can be configured toprovide both transmitting and receiving functionalities. In anotherexample, transmitting and receiving functionalities can be provided byseparate components.

In FIG. 1, one or more output signals from the transceiver 13 aredepicted as being provided to the antenna 22 via one or moretransmission paths 15. In the example shown, different transmissionpaths 15 can represent output paths associated with different bandsand/or different power outputs. For instance, the two different pathsshown can represent paths associated with different power outputs (e.g.,low power output and high power output), and/or paths associated withdifferent bands. The transmit paths 15 can include one or more poweramplifiers 17 to aid in boosting a RF signal having a relatively lowpower to a higher power suitable for transmission. Although FIG. 1illustrates a configuration using two transmission paths 15, thewireless device 11 can be adapted to include more or fewer transmissionpaths 15.

In FIG. 1, one or more detected signals from the antenna 22 are depictedas being provided to the transceiver 13 via one or more receiving paths16. In the example shown, different receiving paths 16 can representpaths associated with different bands. For example, the four examplepaths 16 shown can represent quad-band capability that some wirelessdevices are provided with. Although FIG. 1 illustrates a configurationusing four receiving paths 16, the wireless device 11 can be adapted toinclude more or fewer receiving paths 16.

To facilitate switching between receive and/or transmit paths, theantenna switch module 12 can be included and can be used electricallyconnect the antenna 22 to a selected transmit or receive path. Thus, theantenna switch module 12 can provide a number of switchingfunctionalities associated with an operation of the wireless device 11.The antenna switch module 12 can include a multi-throw switch configuredto provide functionalities associated with, for example, switchingbetween different bands, switching between different power modes,switching between transmission and receiving modes, or some combinationthereof. The antenna switch module 12 can also be configured to provideadditional functionality, including filtering and/or duplexing ofsignals.

FIG. 1 illustrates that in certain embodiments, the control component 18can be provided for controlling various control functionalitiesassociated with operations of the antenna switch module 12 and/or otheroperating component(s). For example, the control component 18 can aid inproviding control signals to the antenna switch module 12 so as toselect a particular transmit or receive path.

In certain embodiments, the processor 20 can be configured to facilitateimplementation of various processes on the wireless device 11. Theprocessor 20 can be a general purpose computer, special purposecomputer, or other programmable data processing apparatus. In certainimplementations, the wireless device 11 can include a computer-readablememory 19, which can include computer program instructions that may beprovided to and executed by the processor 20. The battery 21 can be anysuitable battery for use in the wireless device 11, including, forexample, a lithium-ion battery.

Printed Circuit Board Structure(s)

Disclosed herein are embodiments of integrated antenna packages ormodules including a closed cavity antenna in a printed circuit board.

FIG. 2 illustrates a wireless device 11 with a system board assembly 23.The system board assembly 23 can have an integrated antenna package ormodule 14 and other component(s) 25 disposed on the system boardassembly 23 according to an embodiment. The integrated antenna packageor module 14 can have one or more closed cavity antenna(s) 160 and oneor more other antenna(s) 110, such as planar antennas, dipole antennas,etc. The system board 23 can be any suitable application board, such asa phone board for a mobile phone. Solder bumps of the antenna in theintegrated antenna module 14 can be in physical contact with one or moreground connections of the system board 23. Accordingly, a shieldingstructure can surround an RF component of the antenna in an integratedantenna module 14 in three dimensions. The shielding structure canprovide shielding between the RF component and the antenna layer 160 ofthe antenna in an integrated antenna module 14. The shielding structurecan provide shielding between the RF component and one or more othercomponents 25 disposed on the system board 23. Accordingly, the RFcomponent can be shielded from radiation emitted by the one or moreother components 25. At the same time, the other component(s) 25 can beshielded from radiation emitted from the RF component.

FIG. 3 shows one embodiment of a multi-layer printed circuit boardmodule 100. The module 100 includes a top metal layer 110, anintermediate metal layer 135 and a bottom metal layer 170. The bottommetal layer 170 can be disposed over a substrate material 155. Theintermediate metal layer 135 can be adhered by an adhesive layer 140 toa core layer 145, which can be adhered to the bottom metal layer 170 byan adhesive layer 150. The top metal layer 110 can be disposed on a corelayer 120, which is attached to the intermediate metal layer 135 by anadhesive layer. The core layer 120 can be a pre-pressed layer structurehaving, for example, a prepreg layer disposed between copper foillayers. In some embodiments, the top metal layer 110 can be excluded.With continued reference to FIG. 3, the core layer 145 can have a cavity160 defined therein between the adhesive layers 140, 150. In oneembodiment, the cavity 160 can be a closed cavity filled with air. Inanother embodiment, the cavity 160 can enclose a component, or be filledwith another material (e.g., high dielectric ceramics, high dielectricresonator, etc.). A pair of vias 185A can interconnect the intermediateand bottom metal layers 135, 170 and a through via 185B can interconnectthe top metal layer 110 to a ground layer, for example via connectors180.

In one embodiment, the top metal layer 110 can be a planar antenna, forexample, that radiates in one direction, for example upwardly.Optionally, the cavity 160 can also be an antenna, for example, thatradiates in a second direction (e.g., different than the firstdirection), such as laterally (to the side in FIG. 3).

FIG. 4A is a flow diagram of a method 200 for making the printed circuitboard module 100 of FIG. 3. A core layer 145 is provided at step 210.The core layer 145 can have a metal layer (e.g., copper) 147, 149 over atop surface and a bottom surface of the core layer 145.

At step 220, the metal layers 147, 149 can be removed from the corelayer 145, such as via an etching process, and a cavity 160 can beformed. Optionally, the cavity 160 can be formed by drilling (e.g.,using a mechanical drill, using a laser drill) through the core layer145. In another embodiment, the cavity 160 can be formed using amechanical punch tool to punch the cavity 160 into the core layer 145.

At step 230, an adhesive layer 140, 150 can be disposed over the top andbottom surfaces of the core layer 145, and metal (e.g., copper, silver,etc.) layers 135, 170 can be disposed over the adhesive layer 140, 150,for example in a Resin Coated Copper (RCC) lamination process. In oneembodiment, the adhesive 140, 150 can be a thin and no-flow or low-flowresin to inhibit (e.g., prevent) resin flow inside of the cavity 160.The A vent hole 162 can be formed (e.g., via drilling, such asmechanical or laser drilling) in the cavity 60 to allow air to vent fromthe cavity 60 when the structure is heated during the manufacturingprocess (e.g., lamination process), thereby inhibiting (e.g.,preventing) damage to the PCB structure from expansion forces applied bythe air in the cavity 160 when heated. The vent hole 162 can optionallybe drilled vertically through the adhesive layer 140 and metal layer135. In another embodiment, the vent hole 162 can optionally be drilledhorizontally through the core layer 145.

At step 240, one or more vias 185A can be formed through the metallayers 135, 170, adhesive layers 140, 150 and core layer 145. The one ormore vias 185A can be optionally be formed via drilling (e.g.,mechanical drilling, laser drilling).

At step 250, the metal layers 135, 170 (e.g., copper layers) can bepatterned by removing metal from the metal layers 135, 170 in a desiredmanner to provide the desired electrical connection between the metallayers 135, 170. In one embodiment, the metal layers 135, 170 can bepatterned using an etching process. In other embodiments, other suitableprocesses (e.g., ablation) can be used for the patterning process.

At step 260, outer layers can be applied. In the illustrated embodiment,a substrate material can be disposed under the metal layer 170, and acore layer 120 and top metal layer 110 can be disposed over the metallayer 135 to define the printed circuit board module 100.

FIG. 4B show a block diagram of the method 200 for manufacturing theclosed cavity printed circuit board 100. At block 210, the core layer145 is provided and the top and bottom metal layer are removed from thecore layer 145. At block 220, an opening is formed in the core layer 145(e.g., by drilling through the core layer 145). At block 230, the corelayer 145 is laminated (e.g., using a Resin Coated Copper process) toclose the previously formed opening to define the closed cavity 160 inthe core layer 145. At block 240, one or more via 185A are formed in thecore layer 145. At block 250, the metal layers 135, 170 (e.g., copperlayers) applied in the lamination step are patterned by removing metalfrom the metal layers 135, 170 in a desired manner to provide thedesired electrical connection between the metal layers 135, 170. Atblock 260, one or more outer layers can be applied to complete theprinted circuit board 100.

FIG. 5 shows another embodiment of a multi-layer printed circuit boardmodule 100′ that is similar to the printed circuit board module 100 inFIG. 3, except as described below. The printed circuit board 100′ isconstructed similar to the printed circuit board 100 shown in FIG. 3,except as noted below. Therefore, the references numerals used todesignate the various components of the printed circuit board 100′ areidentical to those used for identifying the corresponding components ofthe printed circuit board 100 in FIG. 3, except that a “′” has beenadded to the reference numerals.

The module 100′ includes a top metal layer 110′, an intermediate metallayer 135′ and a bottom metal layer 170′. The bottom metal layer 170′can be disposed over a substrate material 155′. The intermediate metallayer 135′ can be adhered by an adhesive layer 140′ to a core layer145′, which can be adhered to the bottom metal layer 170′ by an adhesivelayer 150′. The top metal layer 110′ can be disposed on a core layer120′, which is attached to the intermediate metal layer 135′. In someembodiments, the top metal layer 110′ can be excluded. With continuedreference to FIG. 5, the core layer 145′ can have a cavity 160″ definedtherein between the adhesive layers 140′, 150′. In one embodiment, thecavity 160″ can be a closed cavity filled with air. One or more vias185A′ can interconnect the intermediate and top metal layers 135′, 110′and one or more vias 185B′ can interconnect the intermediate and bottommetal layers 135′, 170′, which can connect to a ground layer, forexample via connectors 180′.

In one embodiment, the top metal layer 110′ can be a planar antenna, forexample, that radiates in one direction, for example upwardly.Optionally, the cavity 160′ can also be an antenna, for example, thatradiates in a second direction (e.g., different than the firstdirection), such as laterally (to the side in FIG. 5).

FIG. 6A is a flow diagram of a method 200′ for making the printedcircuit board module 100′ of FIG. 5, which is similar to the method 200in FIG. 4A, except as described below. Therefore, the referencesnumerals used to designate the various steps of the method 200′ areidentical to those used for identifying the corresponding steps of themethod 200 in FIG. 4A, except that a “′” has been added to the referencenumerals.

A printed circuit board structure 500 is provided that has an opencavity 160′ at step 210′. The cavity 160″ can be defined in a core layer145′, which can be attached over a metal layer 170′ (e.g., copper) withan adhesive layer 150′. The metal layer 170′ can be disposed on asubstrate material 155′.

At step 220′, an adhesive layer 130′ is disposed over the core layer145′ to cover the exposed cavity 160″. In one embodiment, the adhesivelayer 130′ can be a low-flow or no-flow resin material to inhibit (e.g.prevent) excessive flow of resin into the cavity 160″. In anotherembodiment, a prepreg layer can be used instead of the adhesive layer130′ to cover the exposed cavity 160″. An air vent 162′ can be appliedto the cavity 160″ (e.g., via drilling, such as mechanical or laserdrilling, as described above) in order to inhibit (e.g., prevent) damageto the cavity or PCB structure from the expansion of air in the closedcavity 160″ during heating of the structure (e.g., during themanufacturing process).

At step 230′, a two-layer board 510 can be provided. The two-layer board510 can have a core layer 120′ with metal layers 110′, 135′ on top andbottom surfaces thereof, and can have one or more vias 185A′ thatinterconnect the metal layers 110′, 135′.

At step 240′, the 2-layer board can be laminated over printed circuitboard structure 500 with the adhesive layer 130′ in between.

At step 250′, through bores 185A′ can be formed, for example via laserdrilling.

At step 260′, plating of the bores 185A′ is performed to fill at least aportion of the bores 185A′ with metal to define vias 185A′ thatelectrically connect the printed circuit board structure 500 with thetwo-layer board 510.

FIG. 6B show a block diagram of the method 200′ for manufacturing theclosed cavity printed circuit board 100′. At block 210′, an open cavityPCB 500 is provided. At block 220′, an adhesive layer 130′ is appliedover the open cavity PCB 500 to close the cavity 160″. At block 230′, a2-layer board 510 is provided. At block 240′, the 2-layer board 510 islaminated over the over the PCB 500. At block 250′, bores for one ormore vias 185A′ 1856′ are formed. At block 260, the bores are plated todefine the vias 185A′, 1856′.

As discussed above, the top metal layers 110, 110′ can be a planarantenna. The metal layers 110, 110′ can include any suitable antennashape and size. FIGS. 7A and 7B illustrate example antennas packages100, 100′ according to certain embodiments. For instance, the antenna110, 110′ can be U-shaped as shown in FIG. 7A. The antenna 110, 110′ inFIG. 7A can be a folded quarter wave antenna. As another example, theantenna 110, 110′ can be a meandering shape as shown in FIG. 7B. Theantenna can be coil shaped in certain implementations. The antenna canbe a loop antenna in some implementations. The antenna 110, 110′ canserve as an antenna for a system on a chip. Such antennas can beconfigured to transmit and/or receive Bluetooth and/or ZigBee signals,for example. The antenna of the antenna layer can be in communicationwith transmit and/or receive circuitry by way of one or more wire bonds,by way of one or more vias extending through a substrate over which theantenna is disposed as discussed above, by way of magnetic coupling, orany combination thereof.

While certain embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms. Furthermore, various omissions, substitutions and changes in thesystems and methods described herein may be made without departing fromthe spirit of the disclosure. For example, one portion of one of theembodiments described herein can be substituted for another portion inanother embodiment described herein. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the disclosure. Accordingly, thescope of the present inventions is defined only by reference to theappended claims.

Features, materials, characteristics, or groups described in conjunctionwith a particular aspect, embodiment, or example are to be understood tobe applicable to any other aspect, embodiment or example described inthis section or elsewhere in this specification unless incompatibletherewith. All of the features disclosed in this specification(including any accompanying claims, abstract and drawings), and/or allof the steps of any method or process so disclosed, may be combined inany combination, except combinations where at least some of suchfeatures and/or steps are mutually exclusive. The protection is notrestricted to the details of any foregoing embodiments. The protectionextends to any novel one, or any novel combination, of the featuresdisclosed in this specification (including any accompanying claims,abstract and drawings), or to any novel one, or any novel combination,of the steps of any method or process so disclosed.

Furthermore, certain features that are described in this disclosure inthe context of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresthat are described in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations, one or more features from a claimedcombination can, in some cases, be excised from the combination, and thecombination may be claimed as a subcombination or variation of asubcombination.

Moreover, while operations may be depicted in the drawings or describedin the specification in a particular order, such operations need not beperformed in the particular order shown or in sequential order, or thatall operations be performed, to achieve desirable results. Otheroperations that are not depicted or described can be incorporated in theexample methods and processes. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the described operations. Further, the operations may berearranged or reordered in other implementations. Those skilled in theart will appreciate that in some embodiments, the actual steps taken inthe processes illustrated and/or disclosed may differ from those shownin the figures. Depending on the embodiment, certain of the stepsdescribed above may be removed, others may be added. Furthermore, thefeatures and attributes of the specific embodiments disclosed above maybe combined in different ways to form additional embodiments, all ofwhich fall within the scope of the present disclosure. Also, theseparation of various system components in the implementations describedabove should not be understood as requiring such separation in allimplementations, and it should be understood that the describedcomponents and systems can generally be integrated together in a singleproduct or packaged into multiple products.

For purposes of this disclosure, certain aspects, advantages, and novelfeatures are described herein. Not necessarily all such advantages maybe achieved in accordance with any particular embodiment. Thus, forexample, those skilled in the art will recognize that the disclosure maybe embodied or carried out in a manner that achieves one advantage or agroup of advantages as taught herein without necessarily achieving otheradvantages as may be taught or suggested herein.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements, and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements, and/or steps are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or without userinput or prompting, whether these features, elements, and/or steps areincluded or are to be performed in any particular embodiment.

Conjunctive language such as the phrase “at least one of X, Y, and Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to convey that an item, term, etc. may beeither X, Y, or Z. Thus, such conjunctive language is not generallyintended to imply that certain embodiments require the presence of atleast one of X, at least one of Y, and at least one of Z.

Language of degree used herein, such as the terms “approximately,”“about,” “generally,” and “substantially” as used herein represent avalue, amount, or characteristic close to the stated value, amount, orcharacteristic that still performs a desired function or achieves adesired result. For example, the terms “approximately”, “about”,“generally,” and “substantially” may refer to an amount that is withinless than 10% of, within less than 5% of, within less than 1% of, withinless than 0.1% of, and within less than 0.01% of the stated amount. Asanother example, in certain embodiments, the terms “generally parallel”and “substantially parallel” refer to a value, amount, or characteristicthat departs from exactly parallel by less than or equal to 15 degrees,10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree.

The scope of the present disclosure is not intended to be limited by thespecific disclosures of preferred embodiments in this section orelsewhere in this specification, and may be defined by claims aspresented in this section or elsewhere in this specification or aspresented in the future. The language of the claims is to be interpretedbroadly based on the language employed in the claims and not limited tothe examples described in the present specification or during theprosecution of the application, which examples are to be construed asnon-exclusive.

What is claimed is:
 1. A method of making a printed circuit boardcomprising: providing a printed circuit board structure having an opencavity defined in a core layer; laying a cover layer over the printedcircuit board structure so that the cover layer extends over the opencavity to cover the open cavity and define a closed cavity antennafilled with air; laminating a board over the cover layer, the boardhaving at least two layers; forming one or more through bores throughthe cover layer; and plating the one or more through bores to form oneor more vias between a top metal layer of the board and a bottom metallayer of the board.
 2. The method of claim 1 wherein the board is a2-layer board.
 3. The method of claim 1 wherein the cover layer is aprepreg layer.
 4. The method of claim 1 wherein the cover layer is ano-flow or low-flow adhesive layer.
 5. The method of claim 1 wherein thecover layer defines a top wall of the closed cavity.
 6. The method ofclaim 1 wherein forming one or more through bores includes forming thebores with a laser.
 7. The method of claim 1 further comprising forminga vent hole between the closed cavity and an outer edge of the printedcircuit board to allow air to exit the closed cavity, thereby inhibitingdamage to the closed cavity from increased pressure from air in theclosed cavity during a heating process.
 8. The method of claim 1 whereinthe closed cavity antenna is U shaped.
 9. The method of claim 1 whereinthe closed cavity antenna is coil shaped.
 10. The method of claim 1wherein the closed cavity antenna is a loop antenna.
 11. A closed-cavityprinted circuit board comprising: a printed circuit board structurehaving an open cavity defined in a core layer; a cover layer over theprinted circuit board structure so that the cover layer extends over theopen cavity to cover the cavity and define a closed cavity antennafilled with air; a board over the cover layer, the board having at leasttwo layers; one or more through bores through the cover layer; and oneor more plated through bores to form one or more vias between a topmetal layer of the board and a bottom metal layer of the board.
 12. Theclosed-cavity printed circuit board of claim 11 wherein the board is a2-layer board.
 13. The closed-cavity printed circuit board of claim 11wherein the cover layer is a prepreg layer.
 14. The closed-cavityprinted circuit board of claim 11 wherein the cover layer is a no-flowor low-flow adhesive layer.
 15. The closed-cavity printed circuit boardof claim 11 wherein the cover layer defines a top wall of the closedcavity.
 16. The closed-cavity printed circuit board of claim 11 whereinforming one or more through bores includes forming the bores with alaser.
 17. The closed-cavity printed circuit board of claim 11 furthercomprising a vent hole between the closed cavity and an outer edge ofthe printed circuit board to allow air to exit the closed cavity,thereby inhibiting damage to the closed cavity from increased pressurefrom air in the closed cavity during a heating process.
 18. Theclosed-cavity printed circuit board of claim 11 wherein the closedcavity antenna is U shaped.
 19. The closed-cavity printed circuit boardof claim 11 wherein the closed cavity antenna is coil shaped.
 20. Theclosed-cavity printed circuit board of claim 11 wherein the closedcavity antenna is a loop antenna.